1. Field of the Invention
The present invention relates to a vacuum treating method and apparatus.
2. Description of the Prior Art
In the past, as a treating method used on plastic products prior to coating, it has been known, for example, in Japanese Patent Application Laid-Open No. 141340/1979 and the like, to apply a low temperature plasma treatment using oxygen gases under a high vacuum atmosphere, 0.1 to 5 Torr.
In the above-described prior art, a first exhaust chamber, a vacuum chamber and a second exhaust chamber are arranged in order, and when a material to be treated is moved from the first exhaust chamber to the vacuum chamber, the first exhaust chamber is reduced in pressure from atmospheric pressure to that degree of vacuum which is suitable for treatment thereby to have degrees of vacuum of the first exhaust chamber and vacuum chamber equalized with each other, after which the first exhaust chamber and vacuum chamber are brought into communication with each other and the material is moved. Therefore, where a material or article to be treated is large in size for example such as a bumper of an automobile, there have been encountered inconveniences in that an increase in volume of the first exhaust chamber and vacuum chamber is followed by an aspirator or suction means for obtaining a predetermined degree of vacuum becoming large-sized, an operating cost increasing, and preparatory time prior to treatment work becoming lengthy, resulting in the lowering of productivity.